Problem: Express this product in scientific notation: $(4.20\times 10^{1})\times (2.00\times 10^{3})$
Start by collecting like terms together. $= (4.20\times 2.00) \times (10^{1}\times 10^{3})$ When multiplying exponents with the same base, add the powers together. $= 8.4 \times 10^{1\,+\,3}$ $= 8.4 \times 10^{4}$